tonight that federal law enforcement source confirms that prosecutors are preparing search warrants. most likely to be executed tomorrow. a limited number in the boston area in their continuous search for evidence in this case. that suggests that there are at least some leads, but mr. deloria made clear the investigation is in its infancy, and the number of -- the search for suspects and motives remains wide open. >> leiter, what does this mean? i mean, is there anything here that's a breakthrough? the public clearly wants to see what happened and why, but at the same time, you don't want to rush and -- and bring in something or someone that you can't really get the evidence to back up. so is there any breakthrough at all in any of this? >> well, it's still relatively early, but i think there are two things that are really important. the type of bomb doesn't tell us all that much. lots of different groups have used this bomb. you can find out how to make a pressure cooker bomb on the internet. >> wait a minute. you can find out how to make this bomb on the internet. so we don't -- we can'